Chemical mechanical polishing cleaning system with temperature control for defect reduction

ABSTRACT

A cleaning system includes at least one cleaning module configured to receive a substrate after a chemical mechanical polishing (CMP) process and to remove contaminants on the substrate using a cleaning solution. The cleaning system further includes a cleaning solution supply system configured to supply the cleaning solution to the at least one cleaning module. The cleaning solution supply system includes at least one temperature control system. The at least one temperature control system includes a heating device configured to heat the cleaning solution, a cooling device configured to cool the cleaning solution, a temperature sensor configured to monitor a temperature of the cleaning solution, and a temperature controller configured to control the heating device and the cooling device.

BACKGROUND

Chemical mechanical polishing (CMP) is widely used in the fabrication ofintegrated circuits. As an integrated circuit is built up layer by layeron a surface of a substrate (e.g., a semiconductor wafer), CMP processesare used to planarize the topmost layer or layers to provide a planarsurface for subsequent fabrication steps. CMP processes are carried outby polishing the substrate surface against a polishing pad as a slurrycontaining both abrasive particles and reactive chemicals is applied tothe polishing pad. The relative movement of the polishing pad and thesubstrate coupled with the reactive chemicals in the slurry allows theCMP process to planarize the substrate surface by means of both physicaland chemical forces. CMP is an effective way to achieve global waferplanarization for advanced integrated circuits.

BRIEF DESCRIPTION OF THE DRAWINGS

Aspects of the present disclosure are best understood from the followingdetailed description when read with the accompanying figures. It isnoted that, in accordance with the standard practice in the industry,various features are not drawn to scale. In fact, the dimensions of thevarious features may be arbitrarily increased or reduced for clarity ofdiscussion.

FIG. 1 is a schematic diagram of a chemical mechanical polishing (CMP)system for processing a substrate, in accordance with some embodiments.

FIG. 2 is schematic diagrams of cleaning modules in the CMP system, inaccordance with some embodiments.

FIG. 3A is a schematic diagram of a cleaning solution supply system, inaccordance with some embodiments.

FIG. 3B is a schematic diagram of a cleaning solution supply system, inaccordance with some embodiments.

FIG. 4 is a flowchart of a method of cleaning a substrate after a CMPprocess, in accordance with some embodiments.

FIG. 5 is a diagram of a control system for controlling a CMP system, inaccordance with some embodiments.

DETAILED DESCRIPTION

The following disclosure provides many different embodiments, orexamples, for implementing different features of the provided subjectmatter. Specific examples of components and arrangements are describedbelow to simplify the present disclosure. These are, of course, merelyexamples and are not intended to be limiting. For example, the formationof a first feature over or on a second feature in the description thatfollows may include embodiments in which the first and second featuresare formed in direct contact, and may also include embodiments in whichadditional features may be formed between the first and second features,such that the first and second features may not be in direct contact. Inaddition, the present disclosure may repeat reference numerals and/orletters in the various examples. This repetition is for the purpose ofsimplicity and clarity and does not in itself dictate a relationshipbetween the various embodiments and/or configurations discussed.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The apparatus may be otherwise oriented (rotated 90 degreesor at other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly.

CMP processes are widely used for fabrication of various components ofintegrated circuits. For example, CMP processes are used to planarizeinter-layer and inter-metal dielectric layers. CMP processes are alsoused to form conductive lines that interconnect the components ofintegrated circuits. CMP processes, however, leave contaminants on thesurfaces of the substrate. The contaminants are comprised of residues ofabrasive particles from the slurry, which may include alumina or silica,along with residues of chemical additives, such as oxidizing agents,chelating agents, corrosion inhibitors, stabilizing agents, and/or pHadjusting agents, added to the slurry. In addition, the contaminants maycomprise residues of reaction products of the slurry and the polishedsurfaces and particles from the polishing pad. These contaminantsadversely affect device reliability and reduce the manufacturing processyield.

Following the CMP process, substrates are subjected to a cleaningprocess in which the substrates go through a post-CMP cleaner consistingof several cleaning modules. The cleaning modules uses various particleremoval technologies such as megasonic cleaning, scrub cleaning, andbrush cleaning to remove contaminants from surfaces of the substratesbefore continuing the construction of the integrated circuits. Asscaling of the device sizes, it becomes more important to thoroughlyremove CMP residues on a substrate because failure to do so causesdefects in the integrated circuits.

In some embodiments, to help to enhance the cleaning efficacy, atemperature control system for adjusting temperatures of a cleaningsolution used in the post-CMP cleaning process is provided in a CMPcleaning system. The temperature control system includes a heatingdevice for heating the cleaning solution to a temperature above anambient temperature, e.g., between about 30° C. and about 100° C., and acooling device for cooling the cleaning solution to a temperature belowthe ambient temperature, e.g., between about −10° C. and about 10° C.Compared to removing CMP contaminants using a cleaning solution at anambient temperature, the post-CMP cleaning process uses a heated or acooled cleaning solution which allows more thorough removal of CMPcontaminants, and as a result, the overall device yield and devicereliability are improved.

FIG. 1 is a schematic diagram of a CMP system 100 for processing asubstrate 102, in accordance with some embodiments. In some embodiments,the CMP system 100 includes a factory interface 104, a polishing system106, and a cleaning system 108. In some embodiments, the CMP systemfurther includes a controller 160. The controller 160 is coupled to thevarious components of the CMP system 100 to facilitate control of theplanarizing, cleaning, and transfer processes.

The factory interface 104 includes an interface robot 112 and one ormore substrate cassettes 114. The interface robot 112 is adapted totransfer substrates 102 between the substrate cassettes 114, thecleaning system 108, and an input module 116. The input module 116 ispositioned to facilitate transfer of substrates 102 between thepolishing system 106 and the factory interface 104.

The polishing system 106 is configured to polish a surface of asubstrate 102. In some embodiments, the polishing system 106 includes atransfer station 122, a carousel 124 that supports a plurality ofsubstrate carriers 126 and a plurality of polishing stations 128.

The transfer station 122 generally includes a transfer robot 132, aninput buffer station 134, an output buffer station 136, and a load cupassembly 138. The input buffer station 134 receives a substrate 102 froma loading robot 140 that is located on a periphery of the polishingsystem 106. The transfer robot 132 moves the substrate 102 from theinput buffer station 134 to the load cup assembly 138 where thesubstrate 102 is transferred to a substrate carrier 126.

The carousel 124 includes a plurality of arms 124 a each supporting asubstrate carrier 126. Two of the arms 124 a depicted in FIG. 1 areshown in phantom such that the transfer station 122 and a substrate 102each held by a corresponding substrate carrier 126 can be seen. Thecarousel 124 is rotatable to move the substrate carriers 126 arounddifferent polishing stations 128 and also from and back to the transferstation 122.

Each polishing station 128 is configured to polish a substrate 102 thatis held by a corresponding substrate carrier 126. In some embodiments,the polishing stations 128 are operated to perform a same processingtask on different substrates 102. Alternatively, in some embodiments,the polishing stations 128 are operated independently to allow differentprocessing tasks to be performed on different substrates 102 at the sametime. Each polishing station 128 includes a polishing pad 142 supportedby a platen (not shown), a slurry dispensing arm 144 configured todispense a slurry to the polishing pad 142, and a pad condition 146configured to restore the roughness of the polishing pad 142.

The slurry includes abrasive particles that are used in mechanicalpolishing of the substrate 102 and one or more chemicals such asoxidizing agents, chelating agents, corrosion inhibitors, stabilizingagents, and/or pH adjusting agents that are used in chemical polishingof the substrate 102. During the CMP process, within each polishingstation 128, the slurry dispensing arm 144 dispenses the slurry onto thepolishing surface of the polishing pad 142. The substrate carrier 126then presses a substrate 102 against the polishing pad 142 as one orboth of the polishing pad 142 and the substrate carrier 126 are rotatedwith respect to each other. The combined mechanical force and chemicalforce polishes the surface of the substrate 102 until an endpoint forthe CMP operation is reached.

After the CMP process, the contaminants are left on the surface of thesubstrate 102. In some embodiments, the contaminants include residues ofthe abrasive particles and chemical additives from the slurry, andresidues from the polished surfaces. These contaminants need to beremoved using the cleaning system 108 prior to a subsequent processing.

The cleaning system 108 includes a plurality of cleaning modules 150configured to perform a multi-stage cleaning process. As the substrate102 is transported through the different cleaning modules 150, thecleaning system 108 removes contaminants from the substrates 102 thatremain on surfaces of the substrate 102 after polishing. The cleaningsystem 108 further includes a drying module 152 configured to dry thesubstrate 102 at the end of the cleaning sequence. In some embodiments,the drying module 152 is a spin-rinse-dry module within which thesubstrate 102 is rinsed with deionized wafer and then dried beforeexiting the cleaning system 108. A substrate handler 154 is operable toretrieve a substrate 102 from the polishing system 106 after polishingand to transfer the substrate 102 sequentially through the plurality ofcleaning modules 150 and the drying module 152. An output module 156 isadapted to facilitate substrate transfer between the cleaning system 108and the substrate cassettes 114 by the interface robot 112 after thepost-CMP cleaning process.

In operation, the CMP system 100 is initiated with a substrate 102 beingtransferred from one of the substrate cassettes 114 to the input module116 by the interface robot 112. The loading robot 140 then moves thesubstrate 102 to the transfer station 122 of the polishing system 106.The substrate 102 is loaded into the substrate carriers 126 and is movedover and polished against the polishing pad 142. Once the substrate 102is polished, the substrate 102 is returned to the transfer station 122where the loading robot 140 transfers the substrate 102 from thepolishing system 106 to the input module 116. The substrate handler 154then retrieves the substrate 102 from the input module 116 and transfersthe substrate 102 through the cleaning modules 150 of the cleaningsystem 108. After being cleaned in the cleaning system 108, thesubstrate 102 is returned to one of the substrate cassettes 114 by theinterface robot 112.

In some embodiments, the cleaning modules 150 utilized in the cleaningsystem 108 includes a megasonic cleaning module 150 a, a pre-cleaningmodule 150 b, and a brush cleaning module 150 c. The multiple cleaningmodules 150 a, 150 b, 150 c are configured to perform a multi-stagesequential post-CMP cleaning process on a substrate 102 using differentcleaning techniques. The cleaning modules 150 a, 150 b, 150 c arediscussed in more detail below with reference to FIG. 2 . Although threecleaning modules 150 a, 150 b, 150 c are illustrated and described, itshould be understood that the cleaning system 108 may comprise anynumber of cleaning modules.

FIG. 2 is schematic diagrams of cleaning modules 150 a, 150 b, 150 c, inaccordance with some embodiments. The cleaning modules 150 a, 150 b, 150c are in fluidic communication with one or more cleaning solution supplysystems 300. The cleaning solution supply system 300 is described inmore detail below with respect to FIG. 3 . In some embodiments, and asshown in FIG. 2 , all of the cleaning modules 150 a, 150 b, and 150 care in fluidic communication with a single cleaning solution supplysystem 300. Alternatively, in some embodiments, each of the cleaningmodules 150 a, 150 b, and 150 c is in fluidic communication with acleaning solution supply system 300.

The megasonic cleaning module 150 a is positioned adjacent to theloading robot 140 (FIG. 1 ). The megasonic cleaning module 150 areceives one or more substrates 102 which have been polished by thepolishing system 106 (FIG. 1 ). In the megasonic cleaning module 150 a,one or more substrates 102 are immersed in a cleaning solution (a singlesubstrate 102 is shown). A source of megasonic energy is activated toagitate the cleaning solution and create a cleaning action at theexposed surfaces of one or more substrates 102.

In some embodiments, and as in FIG. 2 , the megasonic cleaning module150 a includes a tank 212, such as a quartz tank, which is suitable tohold a cleaning solution therein. A holder 214 is disposed at the bottomof the tank 212 and is configured to vertically support the substrate102 within a cleaning solution. A transducer (not shown) is placed inphysical proximity to the tank 212 so that, once activated, thetransducer transmits high frequency acoustic energy into the cleaningsolution to agitate the cleaning solution. In some embodiments, theacoustic energy has a frequency in a range from about 500 kHz to about2.5 MHz. During the megasonic cleaning stage, the megasonic energyagitates the cleaning solution to dislodge contaminants from thesurfaces of the substrate 102 into the cleaning solution. The dislodgedcontaminants are transported out of the tank 212 into an overflow region216 through the overflow of the cleaning solution.

The tank 212 includes an input port 218 for introduction of the cleaningsolution into the tank 212. The input port 218 is connected to an inputfeed pipe 219 which is in fluidic communication with a cleaning solutionsupply system, e.g., cleaning solution supply system 300.

The pre-cleaning module 150 b is arranged adjacent to the megasoniccleaning module 150 a. The pre-cleaning module 150 b receives thesubstrate 102 which has been cleaned by the megasonic cleaning module150 a. In the pre-cleaning module 150 b, a front side surface (i.e., thedevice side surface) of the substrate 102 is scrubbed to remove some ofthe contaminants from the substrate 102. After the substrate 102 hasbeen processed using the pre-cleaning module 150 b, the substrate 102 isautomatically transferred to the brush cleaning module 150 c.

As shown in FIG. 2 , the pre-cleaning module 150 b includes a platen 222configured to support the substrate 102, a scrub pad 224 configured toscrub the front side surface of the substrate 102, and a pair of spraybars 226 configured to spray a cleansing solution via a plurality ofnozzles 227 toward front side and backside surfaces of the substrate 102during the pre-cleaning stage. Each spray bar 226 includes an input port228 for introduction of a cleaning solution to the spray bar 226. Theinput ports 228 are coupled to an input feed pipe 229 which is influidic communication with a cleaning solution supply system, e.g.,cleaning solution supply system 300. During the pre-cleaning stage, thecleaning solution is applied to the front and backside surfaces of thesubstrate 102, the scrub pad 224 is rotated with respect to thesubstrate 102 and scrubs the front side surface of the substrate 102 toremove contaminants from the front side surface of the substrate 102.

In some embodiments, the cleaning solution supplied to the pre-cleaningmodule 150 b is the same as the cleaning solution supplied to themegasonic cleaning module 150 a. In some embodiments, the cleaningsolution supplied to the pre-cleaning module 150 b is different from thecleaning solution supplied to the megasonic cleaning module 150 a. Insome embodiments, the substrate 102 is rinsed before being sent into thepre-cleaning module 150 b if a different chemistry from the megasoniccleaning module 150 a is to be used in the pre-cleaning module 150 b.

The brush cleaning module 150 c is arranged adjacent to the pre-cleaningmodule 150 b. The brush cleaning module 150 c receives the substrate 102which has been cleaned by the pre-cleaning module 150 b. In the brushcleaning module 150 c, both sides (i.e., front side and back side) ofthe substrate 102 are scrubbed to remove contaminants from the substrate102. After the substrate 102 has been processed using the brush cleaningmodule 150 c, the substrate 102 is automatically transferred to thedrying module 152.

As shown in FIG. 2 , the brush cleaning module 150 c includes a pair ofbrushes 232 configured to simultaneously scrub both front and back sidesof the substrate 102, and a pair of spray bars 234 configured to spray acleansing solution via a plurality of nozzles 236 toward opposite sidesof the substrate 102 during the brush cleaning stage. Each spray bar 234includes an input port 238 for introduction of a cleaning solution tothe spray bar 234. The input ports 238 are coupled to an input feed pipe239 which is in fluidic communication with a cleaning solution supplysystem, e.g., cleaning solution supply system 300. During the brushcleaning stage, the brushes 232 are rotated with respective to thesubstrate 102. The brushes 232 scrub the front and backside surfaces ofthe substrate 102 to remove contaminants from both front side surfaceand backside surface of the substrate 102.

In some embodiments, the cleaning solution supplied to the brushcleaning module 150 c is the same as the cleaning solution supplied tothe pre-cleaning module 150 b. In some embodiments, the cleaningsolution supplied to the brush cleaning module 150 c is different fromthe cleaning solution supplied to the pre-cleaning module 150 b. In someembodiments, the substrate 102 is rinsed before being sent into thebrush cleaning module 150 c if a different chemistry from thepre-cleaning module 150 b is to be used in the brush cleaning module 150c.

The type of cleaning solution used depends upon types of contaminants tobe removed from the substrate 102. In some embodiments, deionized (DI)water is used as the cleaning solution. In some embodiments, an acidsuch as dicarboxylic acid, hydrofluoric acid (HF) or phosphoric acid(H₃PO₄) is used as the cleaning solution. In some embodiments, a basesolution such an ammonium hydroxide (NH₄OH) is used as the cleaningsolution. In some embodiments, a mixed solution is used as the cleaningsolution. Examples of the mixed solutions include, but are not limitedto, a mixture of an ammonium hydroxide (NH₄OH), hydrogen peroxide(H₂O₂), and DI water, or a mixture of ammonium hydrogen fluoride (NH₄F),HF, and DI water. In some embodiments, a solvent such as, for example,chloroform (CHCl₃), dichloromethane (CH₂Cl₂), or benzene (C₆H₆), acetone((CH₃)₂CO), or a mixture thereof is used as the cleaning solution.

To increase the cleaning efficiency, depending on types of contaminantsremaining on the substrate 102 and the cleaning solution used, thecleaning solution is either heated to a temperature above an ambienttemperature or cooled to a temperature below an ambient temperaturebefore being supplied to individual cleaning modules 150 a, 150 b, 150c. In some embodiments, the cleaning solution is heated to a temperaturebetween 30° C. to 100° C. In some embodiments, the cleaning solution iscooled to a temperature between −10° C. to 10° C. The heated or cooledcleaning solution helps to remove more contaminants from surfaces of thesubstrate 102 compared to the cleaning solution at the ambienttemperature. As a result, the overall device yield and devicereliability are improved.

FIG. 3A is a schematic diagram of a cleaning solution supply system300A, in accordance with some embodiments. The cleaning solution supplysystem 300A is adapted to supply a cleaning solution to cleaning modules150 a, 150 b, 150 c for removing contaminants that remain on surfaces ofa substrate 102 after the CMP process. In some embodiments, the cleaningsolution supply system 300A includes multiple cleaning fluid sourcetanks, e.g., a first cleaning fluid source tank 302 a and a secondcleaning fluid source tank 302 b, a chemical mixer 320 configured to mixthe chemicals from the cleaning fluid source tanks 302 a, 302 b, and atemperature control system 330 configured to heat or cool the cleaningsolution before supplying to the respective cleaning modules 150 a, 150b, 150 c.

Each of the cleaning fluid source tanks 302 a, 302 b is configured tohold a cleaning fluid for preparing the cleaning solution. In someembodiments, the first cleaning fluid source tank 302 a is a DI watersource tank, and the second cleaning fluid source tank 302 b is achemical source tank. Although two cleaning fluid source tanks areillustrated and described, fewer or more cleaning fluid source tanks canbe provided depending on the compositions of the cleaning solution to beused in each post-CMP cleaning stage.

In some embodiments, the first cleaning fluid source tank 302 a isconfigured to supply DI water directly to the temperature control system330 or alternatively to the chemical mixer 320 for diluting a chemicalfluid from the second cleaning fluid source tank 302 b. The firstcleaning fluid source tank 302 a is coupled to the chemical mixer 320via a pipe 304 and coupled to the temperature control system 330 via apipe 306. A valve 308 is coupled to the pipe 304 and pipe 306. In someembodiments, the valve 308 is a two-way valve such that in one valveposition, the valve 308 fluidly couples the first cleaning fluid sourcetank 302 a to the chemical mixer 320, thus allowing the DI water flowfrom the first cleaning fluid source tank 302 to the chemical mixer 320;and in the other valve position, the valve 308 fluidly couples the firstcleaning fluid source tank 302 a to the temperature control system 330to allow the DI water flow directly from the first cleaning fluid sourcetank 302 a to the temperature control system 330.

The second cleaning fluid source tank 302 b is configured to supply achemical fluid directly to the temperature control system 330 oralternatively to the chemical mixer 320 within which the chemical fluidis mixed with DI water or one or more other chemical fluids. In someembodiments, the chemical fluid includes an acid or a base such as, forexample, hydrofluoric acid (HF), phosphoric acid (H₃PO₄), ammoniumhydroxide (NH₄OH), or ammonium hydrogen fluoride (NH₄F). In someembodiments, the chemical fluid includes a solvent such as, for example,chloroform (CHCl₃), dichloromethane (CH₂Cl₂), or benzene (C₆H₆), acetone((CH₃)₂CO). The second cleaning fluid source tank 302 b is coupled tothe chemical mixer 320 via a pipe 314 and coupled to the temperaturecontrol system 330 via a pipe 306. A valve 318 is coupled to the pipe314 and pipe 316. In some embodiments, the valve 318 is a two-way valvesuch that in one valve position, the valve 318 fluidly couples thesecond cleaning fluid source tank 302 b to the chemical mixer 320,thereby allowing the chemical fluid flow from the second cleaning fluidsource tank 302 b to the chemical mixer 320; and in the other valveposition, the valve 318 fluidly couples chemical source tank 302 bdirectly to the temperature control system 330 to allow the chemicalfluid flow from the second cleaning fluid source tank 302 b to thetemperature control system 330.

The chemical mixer 320 is configured to mix one or more chemical fluidswith the DI water or to mix different chemical fluids. The chemicalmixer 320 includes a mixing element adapted to mix and/or homogenize theflow of fluids prior to transporting the mixture into the temperaturecontrol system 330. In some embodiments, the mixing element is a staticmixer, a dynamic mixer, and inductive mixer, or a mechanical mixer. Thechemical mixer 320 is coupled to the temperature control system 330 viaa pipe 322. A valve 324 is coupled to the pipe 322. The opening of thevalve 324 allows the mixture of chemical fluids to flow from thechemical mixer 320 to the temperature control system 330.

The temperature control system 330 is configured to heat or cool thecleaning solution as the cleaning solution passing through to apredetermined temperature before the cleaning solution is supplied torespective cleaning modules 150 a, 150 b, 150 c, thereby facilitatingthe removal of the contaminants on surfaces of a substrate (e.g.,substrate 102) resulting from the CMP process. In some embodiments, thetemperature control system 330 includes a heating device 332, a coolingdevice 334, a thermal sensor 336, and a temperature controller 338.Although the heating device 332 and the cooling device 334 are depictedas separate elements, it should be understood that the temperaturecontrol system 330 may include a single heating/cooling device whichcontain both heating and cooling elements. In some embodiments, thetemperature control system 330 may include a display, for example, alight emitting diode (LED) display or a liquid crystal display (LCD).The display may show information relating to the temperature controlsystem 330, for example, the temperature from the thermal sensor 336. Insome embodiments, the temperature control system 330 may also include apower source configured to provide power to various components of thetemperature control system 330.

The heating device 332 is configured to heat the cleaning solution to atemperature above the ambient temperature to facilitate removal of thecontaminants from surfaces of the substrate 102. In some embodiments,the heating device 332 is configured to heat the cleaning solution to atemperature between about 30° C. to about 100° C. If the temperature istoo low, the cleaning efficiency of the cleaning solution is decreased,in some instances. If the temperature is too high, there is a risk thatthe substrate is melt or the cleaning solution is boiled, in someinstances. In some embodiments, the heating device 332 is a resistanceheater to generate heat.

The cooling device 334 is configured to cool the cleaning solution to atemperature below the ambient temperature to facilitate removal of thecontaminants from surfaces of the substrate 102. In some embodiments,the cool device 334 is configured to cool the cleaning solution to atemperature between about −10° C. to about 10° C. If the temperature istoo low, there is a risk that the cleaning solution is frozen, in someinstances. If the temperature is too high, the cleaning efficiency ofthe cleaning solution is decreased, in some instances. In someembodiments, the cooling device is a refrigeration compressor togenerate a cooling flow (coolant or de-ionized water).

The temperature sensor 336 is configured to monitor the temperature ofthe cleaning solution, and to provide signals to a temperaturecontroller 338 which controls power to the heating device 332 or thecooling device 334. In some embodiments, the temperature sensor 336 is athermocouple. The thermocouple may include any type thermocouples suchas, for example, type S, B, K, E, J, T, or N. Characteristics of severalstandardized thermocouple types are summarized in Table 1. In someembodiments, the temperature sensor 336 is a resistance temperaturedetector. In some embodiments, the temperature sensor 336 is athermistor.

TABLE 1 Thermocouple Type Sensitivity Operating Range Type S (platinum)10 μV/° C.    0° C.-1750° C. Type B (platinum) 10 μV/° C.  50° C.-1800°C. Type K (chromel-alumel) 41 μV/° C. −200° C.-1200° C. Type E(chromel-constantan) 68 μV/° C. −200° C.-900° C.  Type J(iron-constantan) 55 μV/° C. −40° C.-750° C. Type T (copper-constantan)43 μV/° C. −200° C.-350° C.  Type N (nicrosil-nisil) 39 μV/° C. up to1300° C.

The temperature controller 338 is configured to receive signals from thetemperature sensor 336 and based on the information from the temperaturesensor 336, to control the operation of the heating device 332 and thecooling device 334. In some embodiments, the temperature controller 338adjusts the power delivered to the heating device 332 or the coolingdevice 334 to control the temperature of the cleaning solution, e.g., atarget temperature (i.e., predetermined temperature) that is eitherabove or below the ambient temperature. The target temperature isdetermined based on types of contaminants to be removed. After thetemperate of the cleaning solution has reached the target temperature,the cleaning solution is supplied to respective cleaning modules 150 a,150 b, 150 c via respective input feed pipes 219, 229, 239.

Depending on the type of cleaning solution used in respective cleaningmodules 150 a, 150 b, 150 c and the type of contaminants to be cleaned,in some embodiments, the temperatures of the cleaning solutions that aredelivered to different cleaning modules, i.e., megasonic cleaning module150 a, pre-cleaning module 150 b, brush cleaning module 150 c, are thesame, while in other embodiments, the temperatures of the cleaningsolutions that are delivered to different cleaning modules, i.e.,megasonic cleaning module 150 a, pre-cleaning module 150 b, brushcleaning module 150 c, are different.

FIG. 3B is a schematic diagram of a cleaning solution supply system300B, in accordance with some embodiments. In some embodiments, thedifference between the cleaning solution supply system 300B and thecleaning solution supply system 300A shown in FIG. 3A is that incleaning solution supply system 300B, each cleaning module, i.e.,megasonic cleaning module 150 a, pre-cleaning module 150 b, brushcleaning module 150 c, is provided with a temperature control system 330to control temperatures of the cleaning solution flowed to eachcorresponding cleaning module 150 a, 150 b, 150 c. The cleaning solutionsupply system 300B, thus, allows providing cleaning solutions withdifferent temperatures to respective cleaning modules 150 a, 150 b, 150c at the same time.

FIG. 4 is a flow chart illustrating a method 400 for cleaning asubstrate using a CMP system, e.g., CMP system 100, in accordance withsome embodiments. For illustration, the flow chart will be describedwith the schematic views shown in FIGS. 1-3B. Some of the stagesdescribed can be replaced or eliminated for different embodiments.Additional features can be added in the semiconductor device structure.Some of the features described below can be replaced or eliminated fordifferent embodiments.

The method 400 includes an operation 402 in which one or moresubstrates, e.g., substrates 102, is provided into a polishing systemsuch as polishing system 106. In some embodiments, the substrate 102 istransferred into the polishing system 106 by one or more robots such asinterface robot 112 and loading robot 140 from a substrate cassette 114.

The method 400 continues with operation 404, in which a CMP process isperformed. During the CMP process, a slurry is applied to a polishingpad 142 of the polishing system 106 and the substrate 102 is polished bya polishing pad 142 using the slurry. After polishing, contaminants suchas slurry residues and polishing residues remain on the substrate 102.

The method 400 continues with operation 406, in which after thesubstrate 102 is polished, the substrate 102 is removed from thepolishing system 106 and transferred to the megasonic cleaning module150 a.

The method 400 continues with operation 408, in which a cleaningsolution with a target temperature is supplied from the cleaningsolution supply system 300 into the megasonic cleaning module 150 a.Depending on the type of cleaning solution used, the cleaning solutionis either heated by the heating device 332 or cooled by the coolingdevice 334 in the temperature control system 300 to reach the targettemperature at which the improved contaminant removal efficiency isobtained. The temperature of the cleaning solution is monitored by thetemperature sensor 336. The information provided by the temperaturesensor 336 is used by the temperature controller 338 to control theoperation of the heating device 332 or the cooling device 334.

The method 400 continues with operation 410, in which a first cleaningprocess is performed using the megasonic cleaning module 150 a. Duringthe first cleaning process, the substrate 102 is immersed into theheated or cooled cleaning solution and a megasonic energy is applied tothe cleaning solution to agitate the cleaning solution, therebydislodging contaminants from surfaces of the substrate 102.

The method 400 continues with operation 412, in which after thesubstrate 102 is cleaned using the megasonic module 150 a, the substrate102 is removed from the megasonic module 150 a and transferred into thepre-cleaning module 150 b.

The method 400 continues with operation 414, in which a cleaningsolution with a target temperature is supplied from the cleaningsolution supply system 300 into the pre-cleaning module 150 b. Dependingon the type of cleaning solution used, the cleaning solution is eitherheated by the heating device 332 or cooled by the cooling device 334 inthe temperature control system 300 to reach the target temperature atwhich the improved contaminant removal efficiency is obtained. Thetemperature of the cleaning solution is monitored by the temperaturesensor 336. The information provided by the temperature sensor 336 isused by the temperature controller 338 to control the operation of theheating device 332 or the cooling device 334.

The method 400 continues with operation 416, in which a second cleaningprocess is performed using the pre-cleaning module 150 b. During thesecond cleaning process, a front side surface of the substrate 102 isscrubbed by the cleaning pad 222 as the heated or cooled cleaningsolution is sprayed to both front side surface and backside surface ofthe substrate 102, thereby removing contaminants from surfaces of thesubstrate 102.

The method 400 continues with operation 418, in which after thesubstrate 102 is cleaned using the pre-cleaning module 150 b, thesubstrate 102 is removed from the pre-cleaning module 150 b andtransferred into the brush cleaning module 150 c.

The method 400 continues with operation 420, in which a cleaningsolution with a target temperature is supplied from the cleaningsolution supply system 300 into the brush cleaning module 150 c.Depending on the type of cleaning solution used, the cleaning solutionis either heated by the heating device 332 or cooled by the coolingdevice 334 in the temperature control system 300 to reach the targettemperature at which the improved contaminant removal efficiency isobtained. The temperature of the cleaning solution is monitored by thetemperature sensor 336. The information provided by the temperaturesensor 336 is used by the temperature controller 338 to control theoperation of the heating device 332 or the cooling device 334.

The method 400 continues with operation 422, in which a third cleaningprocess is performed using the brush cleaning module 150 c. During thethird cleaning process, both front side surface and backside surface ofthe substrate 102 are scrubbed by respective cleaning brushes 232 as aheated or cooled cleaning solution is sprayed to the front side andbackside surfaces of the substrate 102, thereby removing contaminantsfrom surfaces of the substrate 102.

The method continues with operation 424, in which after sequentialcleaning stages to substantially remove contaminants from surfaces ofthe substrate 102, the substrate 102 is transferred to the drying module152 where the substrate 102 is rinsed, spun, and dried, for example, byDI water and isopropyl alcohol (IPA).

FIG. 5 is a block diagram of a control system 500 for controlling a CMPsystem 100, in accordance with some embodiments. The control system 500generates output control signals for controlling operation of one ormore components of CMP system 100, in accordance with some embodiments.The control system 500 receives input signals from one or morecomponents of the CMP system 100, in accordance with some embodiments.In some embodiments, the control system 500 is located adjacent CMPsystem 100. In some embodiments, the control system 500 is remote fromthe CMP system, 100. In some embodiments, controller 160 (FIG. 1 ) andcontroller 338 (FIGS. 3A and 3B) are implemented using the controlsystem 500.

Control system 500 includes a processor 502 and a non-transitory,computer readable storage medium 504 encoded with, i.e., storing,computer program code 506, i.e., a set of executable instructions.Computer readable storage medium 504 is also encoded with instructions507 for interfacing with components of CMP system 100. The processor 502is electrically coupled to the computer readable storage medium 504 viaa bus 508. The processor 502 is also electrically coupled to an I/Ointerface 510 by bus 508. A network interface 512 is also electricallyconnected to the processor 502 via bus 508. Network interface 512 isconnected to a network 514, so that processor 502 and computer readablestorage medium 504 are capable of connecting to external elements vianetwork 514. The processor 502 is configured to execute the computerprogram code 506 encoded in the computer readable storage medium 504 inorder to cause control system 500 to be usable for performing a portionor all of the operations as described with respect to CMP system 100.

In some embodiments, the processor 502 is a central processing unit(CPU), a multi-processor, a distributed processing system, anapplication specific integrated circuit (ASIC), and/or a suitableprocessing unit.

In some embodiments, the computer readable storage medium 504 is anelectronic, magnetic, optical, electromagnetic, infrared, and/or asemiconductor system (or apparatus or device). For example, the computerreadable storage medium 504 includes a semiconductor or solid-statememory, a magnetic tape, a removable computer diskette, a random accessmemory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or anoptical disk. In some embodiments using optical disks, the computerreadable storage medium 504 includes a compact disk-read only memory(CD-ROM), a compact disk-read/write (CD-R/W), and/or a digital videodisc (DVD).

In some embodiments, the storage medium 504 stores the computer programcode 506 configured to cause control system 500 to perform theoperations as described with respect to CMP system 100. In someembodiments, the storage medium 504 also stores information needed forperforming the operations as described with respect to CMP system 100,such as a sensor parameter 516, a target temperature parameter 518,and/or a set of executable instructions to perform the operation asdescribed with respect to CMP system 100.

In some embodiments, the storage medium 504 stores instructions 507 forinterfacing with CMP system 100. The instructions 507 enable processor502 to generate operating instructions readable by elements of the CMPsystem 100 to effectively implement the operations as described withrespect to CMP system 100.

Control system 500 includes I/O interface 510. I/O interface 510 iscoupled to external circuitry. In some embodiments, I/O interface 510includes a keyboard, keypad, mouse, trackball, trackpad, and/or cursordirection keys for communicating information and commands to processor502.

Control system 500 also includes network interface 512 coupled to theprocessor 502. Network interface 512 allows control system 500 tocommunicate with network 514, to which one or more other computersystems are connected. Network interface 512 includes wireless networkinterfaces such as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wirednetwork interface such as ETHERNET, USB, or IEEE-1394.

Control system 500 is configured to receive information related to thetemperature sensor, e.g., temperature sensor 336 (FIGS. 3A and 3B),through I/O interface 510. The information is transferred to processor502 via bus 508 and then stored in computer readable medium 504 assensor parameter 516. Control system 500 is configured to receiveinformation related to the target temperature through I/O interface 510.In some embodiments, the target temperature information is received froman operator. The information is stored in computer readable medium 504as target temperature parameter 518.

During operation, in some embodiments, processor 502 executes a set ofinstructions to determine whether the temperature of the cleaningsolution has reached a target temperature. Based on the abovedeterminations, processor 502 generates a control signal to instruct theheating device 332 or the cooling device 334 to adjust the temperatureof the cleaning solution. In some embodiments, the control signal istransmitted using I/O interface 510. In some embodiments, the controlsignal is transmitted using network interface 512.

One aspect of this description relates to a cleaning system. Thecleaning system includes at least one cleaning module configured toreceive a substrate after a chemical mechanical polishing (CMP) processand to remove contaminants on the substrate using a cleaning solution.The cleaning system further includes a cleaning solution supply systemconfigured to supply the cleaning solution to the at least one cleaningmodule. The cleaning solution supply system includes at least onetemperature control system containing a heating device configured toheat the cleaning solution, a cooling device configured to cool thecleaning solution, a temperature sensor configured to monitor atemperature of the cleaning solution, and a temperature controllerconfigured to control the heating device and the cooling device. In someembodiments, the at least one cleaning module includes a megasoniccleaning module configured to remove the contaminants from a front sidesurface and a backside surface of the substrate using megasonic energy.In some embodiments, the at least one cleaning module includes apre-cleaning module configured to remove the contaminants from a frontside surface of the substrate using a pad. In some embodiments, the atleast one cleaning module includes a brush cleaning module configured toremove the contaminants from a front side and a backside of thesubstrate using a pair of brushes. In some embodiments, the heatingdevice is configured to heat the cleaning solution from about 30° C. toabout 100° C. In some embodiments, the cooling device is configured tocool the cleaning solution from about −10° C. to 10° C. In someembodiments, the temperature sensor includes a thermocouple, aresistance temperature detector, or a thermistor. In some embodiments,the cleaning solution includes an acidic solution or a base solution. Insome embodiments, the cleaning solution comprises hydrofluoric acid,phosphoric acid, ammonium hydroxide, hydrogen peroxide, or a mixturethereof. In some embodiments, the cleaning solution includes deionizedwater. In some embodiments, the cleaning solution includes chloroform,dichloromethane, or benzene, acetone, or mixtures thereof.

Another aspect of this description relates to a chemical mechanicalpolishing (CMP) system. The CMP system includes a polishing systemconfigured to polish a substrate. The CMP system further incudes acleaning system configured to remove contaminants remaining on thesubstrate after the substrate has been polished in the polishing system.The cleaning system includes a plurality of cleaning modules. A firstcleaning module of the plurality of cleaning modules is configured toperform a first cleaning process and a second cleaning module of theplurality of cleaning modules is configured to perform a second cleaningprocess. The cleaning system further includes a cleaning solution supplysystem configured to supply a first cleaning solution of a firsttemperature to the first cleaning module and a second cleaning solutionof a second temperature to the second cleaning module. The firsttemperature is different from the second temperature. In someembodiments, the first cleaning solution is different from the secondcleaning solution. In some embodiments, the cleaning solution supplysystem includes a plurality of cleaning fluid source tanks each of whichis configured to hold a cleaning fluid, a chemical mixer configured tomix two or more cleaning fluids from the plurality of cleaning fluidsource tanks, and a temperature control system, wherein the temperaturecontrol system is configured to heat or cool a cleaning solution fromrespective cleaning fluid source tanks or the chemical mixer to apredetermined temperature. In some embodiments, the temperature controlsystem includes a heating device configured to heat the cleaningsolution, a cooling device configured to cool the cleaning solution, atemperature sensor configured to monitor a temperature of the cleaningsolution, and a temperature controller configured to control the heatingdevice and the cooling device.

Yet another aspect of this description relates to a method of cleaning asubstrate following a chemical mechanical polishing (CMP) process. Themethod includes providing a substrate in need of removing CMPcontaminants into a cleaning module, supplying a cleaning solution tothe cleaning module, the cleaning solution having a temperature above orbelow an ambient temperature, and removing the CMP contaminants from thesubstrate using the cleaning solution. In some embodiments, the methodfurther includes heating the cleaning solution from about 30° C. toabout 100° C. using a heating device. In some embodiments, the methodfurther includes cooling the cleaning solution from about −10° C. toabout 10° C. using a cooling device. In some embodiments, the methodfurther includes monitoring the temperature of the cleaning solutionusing a temperature sensor. In some embodiments, the method furtherincludes adjusting the temperature of the cleaning solution based ontypes of the CMP contaminants on the substrate.

The foregoing outlines features of several embodiments so that thoseskilled in the art may better understand the aspects of the presentdisclosure. Those skilled in the art should appreciate that they mayreadily use the present disclosure as a basis for designing or modifyingother processes and structures for carrying out the same purposes and/orachieving the same advantages of the embodiments introduced herein.Those skilled in the art should also realize that such equivalentconstructions do not depart from the spirit and scope of the presentdisclosure, and that they may make various changes, substitutions, andalterations herein without departing from the spirit and scope of thepresent disclosure.

What is claimed is:
 1. A method for processing a substrate, comprising: planarizing a surface of the substrate by a chemical mechanical polishing (CMP) process, the CMP process generating contaminants on the surface of the substrate; placing the substrate in a cleaning module; supplying a cleaning solution from a cleaning solution supply system to the cleaning module, wherein the cleaning solution supply system comprises a temperature control system, the temperature control system comprising: a heating device configured to heat the cleaning solution; a cooling device configured to cool the cleaning solution; a temperature sensor configured to monitor a temperature of the cleaning solution; and a temperature controller configured to control a temperature of the cleaning solution; monitoring a temperature of the cleaning solution; comparing the temperature of the cleaning solution with a target temperature that is determined based on types of the contaminants on the substrate; heating or cooling the cleaning solution until the target temperature is reached; and removing the contaminants from the surface of the substrate using the cleaning solution of the target temperature.
 2. The method of claim 1, wherein heating the cleaning solution comprises heating the cleaning solution to a temperature from about 30° C. to about 100° C. using the heating device.
 3. The method of claim 1, wherein cooling the cleaning solution comprises cooling the cleaning solution to a temperature from about −10° C. to about 10° C. using the cooling device.
 4. The method of claim 1, wherein the temperature of the cleaning solution is monitored by the temperature sensor.
 5. The method of claim 1, wherein the cleaning module comprises a megasonic cleaning module, the method comprising: immersing the substrate into the cleaning solution of the target temperature; and supplying a megasonic energy to the cleaning solution to agitate the cleaning solution, thereby dislodging the contaminants from the surface of the substrate.
 6. The method of claim 5, wherein the cleaning module comprises a pad-cleaning module, the method comprising: spraying the cleaning solution of the target temperature to the surface of the substrate; and scrubbing the surface of the substrate using a cleaning pad to remove the contaminants from the surface of the substrate.
 7. The method of claim 6, wherein the cleaning module comprises a brush-cleaning module, the method comprising: spraying the cleaning solution of the target temperature to front side and backside surfaces of the substrate, wherein the surface of the substrate is the front side surface; and scrubbing the front side and backside surfaces of the substrate using a pair of brushes to remove the contaminants from the surface of the substrate.
 8. The method of claim 7, further comprising: transferring the substrate from the megasonic cleaning module to the pad-cleaning module after the substrate has been cleaned in the megasonic cleaning module; and transferring the substrate from the pad-cleaning module to the brush-cleaning module after the substrate has been cleaned in the pad-cleaning module.
 9. The method of claim 1, further comprising transferring the substrate from the cleaning module to a drying module.
 10. The method of claim 9, further comprising: rinsing the substrate by water or isopropyl alcohol; and drying the substrate.
 11. A method for processing a substrate, comprising: planarizing a surface of the substrate by a chemical mechanical polishing (CMP) process, the CMP process generating contaminants on the surface of the substrate; cleaning the substrate in a first cleaning module with a cleaning solution of a target temperature that is determined based on types of the contaminants on the substrate, wherein the first cleaning module is operated to remove the contaminants from the substrate using a megasonic acoustic energy; cleaning the substrate in a second cleaning module with the cleaning solution of the target temperature, wherein the second cleaning module is operated to remove the contaminants from the substrate by scrubbing a front side surface of the substrate using a cleaning pad; and cleaning the substrate in a third cleaning module with the cleaning solution of the target temperature, wherein the third cleaning module is operated to remove the contaminants from the substrate by simultaneously scrubbing the front side surface and a backside surface of the substrate using a pair of brushes, wherein the cleaning solution of the target temperature is supplied from a cleaning solution supply system comprising a temperature control system operated to produce the cleaning solution of the target temperature, the temperature control system comprising: a heating device configured to heat the cleaning solution; a cooling device configured to cool the cleaning solution; a temperature sensor configured to monitor a temperature of the cleaning solution; and a temperature controller configured to control a temperature of the cleaning solution; and wherein producing the cleaning solution of the target temperature comprises: monitoring a temperature of the cleaning solution; comparing the temperature of the cleaning solution with a target temperature that is determined based on types of the contaminants on the substrate; and heating or cooling the cleaning solution until the target temperature is reached.
 12. The method of claim 11, further comprising preparing the cleaning solution, wherein preparing the cleaning solution comprises mixing a first cleaning fluid from a first tank and a second cleaning fluid from a second tank.
 13. The method of claim 12, wherein the first cleaning fluid and the second cleaning fluid are mixed in a chemical mixer.
 14. The method of claim 12, wherein the first cleaning fluid and the second cleaning fluid are mixed in the temperature control system.
 15. The method of claim 11, wherein heating or cooling the cleaning solution comprises heating the cleaning solution to a temperature from about 30° C. to about 100° C. using the heating device.
 16. The method of claim 11, wherein heating or cooling the cleaning solution comprises cooling the cleaning solution to a temperature from about −10° C. to about 10° C. using the cooling device.
 17. A method for processing a substrate, comprising: performing a chemical mechanical polishing (CMP) process to planarize a surface of the substrate, the CMP process generating contaminants on the surface of the substrate; and performing a multi-stage cleaning process to remove the contaminants from the surface of the substrate, comprising: supply a first cleaning solution of a first temperature to a first cleaning module, the first cleaning module comprising a tank to hold a first cleaning solution therein, a holder configured to vertically support the substrate during cleaning, and a transducer configured to transmit a megasonic acoustic energy to the first cleaning solution to agitate the first cleaning solution performing a first cleaning process using the first cleaning module; supply a second cleaning solution of a second temperature to a second cleaning module, the second cleaning module comprising a platen configured to support the substrate, a cleaning pad configured to scrub a front side surface of the substrate, and a pair of first spray bars configured to spray a second cleaning solution to the front side surface and a backside surface of the substrate, respectively; performing a second cleaning process after the first cleaning process using the second cleaning module; supply a third cleaning solution of a third temperature to a third cleaning module, the third cleaning module comprising a pair of brushes configured to scrub front side and backside surfaces of the substrate, and a pair of second spray bars configured to spay a third cleaning solution to the front side and backside surfaces of the substrate, respectively; and performing a third cleaning process after the second cleaning process using the third cleaning module, wherein each of the first temperature, the second temperature and the third temperature is controlled by a corresponding temperature control system, wherein controlling the first temperature, the second temperature and the third temperature comprise: comparing a temperature of each of the first cleaning solution, the second cleaning solution and the third cleaning solution with a corresponding target temperature that is determined based on types of the contaminants on the substrate; heating or cooling the first cleaning solution to reach the first temperature; heating or cooling the second cleaning solution to reach the second temperature; and heating or cooling the third cleaning solution to reach the third temperature.
 18. The method of claim 17, wherein the corresponding temperature control system comprises: a heating device configured to heat a corresponding first, second or third cleaning solution; a cooling device configured to cool corresponding first, second or third cleaning solution; a temperature sensor configured to monitor the temperature of a corresponding first, second or third cleaning solution; and a temperature controller configured to control the temperature of a corresponding first, second or third cleaning solution.
 19. The method of claim 18, wherein controlling the first temperature, the second temperature or the third temperature comprises monitoring a temperature of each of the first, second and third cleaning solutions using the temperature sensor.
 20. The method of claim 18, wherein the first temperature, the second temperature and the third temperature are the same or different. 